Pressure tank



` vterials.

y"Patented Dec. 26, 1944 sv PATENT OFFICE.

PRESSURE TANK Sterling W. Alderfer, Akron, Ohio, assignor of 'one-halfto Edward D. Andrews, Akron, Ohio Application October 19,1942, SerialNo. 462,628

4 Claims. l (C l. 220-3) The present invention has for its objectimproving the construction `of containers or tanks such as are usedforholding `gases under high i compression. Tanks or containers of thetype with which this invention deals are used forv the holding andstorage of gases which are used for infiating life rafts, life ,belts orcollapsible boats such as form part of the equipment for landingparties. For such uses the gas employed is usually CO2 under such highpressure that it is liquefied in the container.

'The invention may be `adapted to other and `wideruses such,- forexample, as an oxygen tank used in airplanes or by parachutists who haveto bail out at high altitudes. The invention may also be employed inother fields where it may be i desirable to store or transport gasesunder high pressures. l

The present invention is in the nature of an improvement upon the formof tank shown in my Alprior application Serial No. 452,979, led July 30,

1942, to which reference is made.

Prior tothe invention shown in my prior application, tanks which wereuniversally employed were metal cylinders to which a charging andzrelief valve was affixed. `Due to the enormous pressures which these.tanks were required to withstand, the walls were made of a very highgrade metaLusually reinforced by closely placed Wrappings of piano wireor the like. This was an expensive construction and in addition suchvtanks were highly explosiveand if punctured by a bullet or fractured inany other way the walls of the tank would shatter and fly apart, theflying fragments being dangerous to those in the' vicinity. Frequentlythese` tanks are worn by the aviators and theexplosion of the tank mayresult in death or injury to the wearer. VOther objections to the oldform of tank were its cost and the difficulty in securing the requiredma- AIn the tank 4shown inmy former application these objections andhazards were obviated but the capacity of the tank was somewhatrestricted .is also Veasier to manufacture due to the fact that theinterior of the .tank is a rigid cylinder n win be understood that thespense embodif ment of the invention shown herein need not necessarilybe followed in all forms which may incorporate the new and novelfeatures of the invention as set forth in the appended claims, andtherefore changes andl modiiications may be made without departing fromthe invention.

In the drawing in which the best known and preferred embodiment of theinvention is shown:

Fig. 1 is a plan view of a life raft or inflatable boat showing themanner in which the tank is employed when used in connection with thistype of equipment.

Fig. 2 is a vertical section through the tank.

Fig. 3 is a section through the valve.

Fig. 4 is a section on the line 4-4 of Fig. 2.

Instead of employing a coil of tube or piping Vas the storage space forthe compressed gas as in my former construction, the volume issupplemented by a cylinder located Within the coil of tubing, so that agreater total volume is provided in the same bulk. This permits anequivalent body of compressed gas to be confined under reduced pressureor a greater volume at the same pressure as in my former tankconstruction. The property of non-shatterability is retained because thecross-sectional area of the outer coils of pipe is relatively quitesmall and the bursting pressure in that portion of the tank iscomparatively low, and if the tube is broken or punctured. the gas willescape harmlessly. If the bullet penetrates to the inner tank theexplosive force is reduced and the outer coils of piping serve to holdthe rfragments from ying about. i

The construction comprises an interior tank or container shown at Iwhich is preferably made of a soft steel so that it will not shatter asis the case with the Very hard steels which have been used in thesingle-chamber tanks which .have preceded my tank constructions. Thetank provides a core upon which the outer` coils of tubing are wrapped.One end of the tank is provided with a passage 2 through which the tankis iilled and through which gas can escape when the valve 4 is opened.This Valve is of the usual construction shown in Fig. 3 and is attachedto a nipple 6 formed in the end of the tank body I, and leads by theextension 1 to the inflatable body 8 here shown as an inflatable landingboat or raft. The hand valve is indicated at l0.

If the tank is to be used as an oxygen Atank the valve is attached to abreather pipe or the breather pipe and valve may be attached to the freeend of the tubing. For other installations these details may be varied-as found necessary or desirable.

While the inner core or chamber is shown as a cylinder extending for thelength of the tank these details may be varied. It is preferred,however, to form this 'portion of the tank as shown to constitute a formaboutwhich the outer enveloping coils of tubing may be wound. In windingthe tubing about the core, it is desirable,

to prevent undue flattening of the tube, to fill it with water or otherfluid under pressure which is released after the winding operation iscompleted. The core serves to hold the entire tank body rigid which isadvantageous for certain uses and installations. As is shown in thedrawing, the winding of the tube causes it to atten somewhat owing tothe pressure exerted during the winding operation.

At vone end of the tank the tubing I2 is connected to and incommunication with the interior of the core by turning the end ofthetubinginto an aperture in the tank wall and permanently connecting itthereto, preferably by welding. The outer end of the tubing is closedoil' as at I4. The tubing may be of a soft steel, which is preferred,although copper tubing may be employed. The outer diameter of the tubingmay be approximately 1A; inch, or even larger if desired, it beingdesirable to retain a relatively small across sectional area so as toreduce the pressure at any point in the tube wall. Because of the lowerpressure the wall of the tubing may be quite thin, it having been foundthat a tubing 1A, in diameter with a wall thickness of .025 inch is morethan suicient to hold gases under the very high pressures which areemployed in tanks for the purposes set forth. i The tubing is wrappedabout the core in any number of convolutions and layers. As lshown threelayers of tubing, each layer comprising closely packed convolutions,will give a total volumetric capacity in addition to the capacity of thecore or central cylinder to hold a large volume of gas. After the'tubing is completely wrapped it may be coated with a paint or shellacwhich will flow between the interstices of the structure. Also an outercovering or sac I5 may be provided.

It will be appreciated that the number of turns r and layers of thecoiled tubing and the size thereof and the size and shape of the coremay be Varied in accordance with the volumetric capacity desired and thepressures which are intended to be maintained. The advantages of thenon-explosive tank have been retained but the interior hollow core haspermitted a substantial increase in the capacity without losing thatvaluable feature of my prior invention. The outer wrappings of the metaltubing not only serve as a supplementary chamber but also reinforce thewalls of the inner chamber, both by the inherent -strength of the tubeand by the pressure within the tube which oisets the outward pressure onthe walls of the main chamber.

It has also developed that the tank shown herein has especialadvantagesas a container for liquefied gases such, for example, asliquid carbon dioxide. In the ordinary bottle tanks of the prior art,Ythe release of the gas by opening the valve will cause the contents ofthe bottle to freeze solid while a considerable amount of carbon dioxideis left in the tank. This is due to the older types'of container,especially in lling the absorption of heat by the gas as it passesrapidly from the liquid to the gaseous state which congeals theunexpelled contents of the tank so that it is possible to secure only apartial evacuation of the tank. A wholly unexpectedA result occurs witha tank constituted as shown, for tanks of this design do not tend tofreeze up but discharge the entire contents in gaseous, mist or snowform. a.

This result is due to the factthat vthe liquid gas within the exteriorcoils will volatilize first due to the exposed condition of the coil.The gas will flow from the tube through the liquid in the body of thetank and will keep it ina state of violent agitation until all of thecontents arev discharged, which prevents the contents from` freezing asa solid mass. Any liquid gas which is frozen will turn into a ne snowand will be carried out by the gas in tiny snow-like particles and nosolid freezing of the contents of the bottle will occur. This is animmense advantage over life boats or rafts in which it is urgentthat-the full capacity of the tank be released immediately.

What is claimed is:

1. A portable container for holding Aliquefied gas under pressure',comprising a main container having a release valve for dischargingthezcontents of the container, and an auxiliary container for holding aportion of the gas, vsaid auxiliary container being formed of a pipe ofsmaller ndiameter than the main container said pipel being sealed at oneend and communicating atl the other end with the interior of vthe maincontainer and tightly wrapped in a series of'clofsely vadjacent coilsabout the exterior of the main 'container.

2. A portable container for holding liqueed gas under pressure,comprising a'main container 40 having a release valve for dischargingthe contents of the container, and a tube vofrelatively small crosssection one end of which is passed through the wall of the maincontainer and opening therein, thev remainder of theV tube lbeing sealedthroughout, the tube being coiled tightly around the exterior of themain container to surround and serve as a reinforcement. for the ymaincontainer and also as an auxiliary container for liqueed gas.

3. A portable container for holding liquefied gas or the like,comprising a tank, a release valve for discharging the contents of thetank, and a length of tubing one end of which is secured in the wall ofthe tank, the tubing being wrapped against the exterior of the .tank Yina plurality of convolutions the tubing communicating with the interiorof the tank and otherwise sealed throughout, said tubing thereby servingas an auxiliary container for a portion of the liquefied gas.

4. A portable container for holding liqueed gas or the like,- comprisinga tank, a release valve for discharging the contents of the tank, and alength of tubing one end of which is secured inthe'wall of the tank at apoint remote from the release valve, ,the tubing being wrapped againstthe. exterior of the tank in a plurality of convolutions, the tubingcommunicating with the interior of the tank at the point of securementand being otherwise sealed throughout and thereby serving ,as anauxiliary container for a portion of the liqueed gas:

STERLING W. ALDERFER.

